updating for v0 endpoint cleanup

[samnickolay]

• GraphVersionResponse - doesn't return manifest or graph zip, but does include manifest errors
• active_graph_version -> latest_graph_version for GraphLatestResponse
• changed "/organizations/{organization_uid}/graphs/name/{name}/", to "/organizations/{organization_uid}/graphs/slug/{slug}/",
• changed "/organizations/{organization_uid}/environments/name/{name}/", to "/organizations/{organization_uid}/environments/slug/{slug}/",
• changed "/organizations/name/{name}/", to "/organizations/slug/{slug}/",

Corresponding API PR: https://github.com/basis-os/basis-api/pull/645